Well, for starters he is going batshit crazy. He is trying to use the sha for his own gain. Things like that. He is pretty much doing bad and evil things for power, which he thinks the horde wants. The horde does not want to gain power this way, and they turn against him and his most loyal companions.

He's a warlike douche, and he's destroying everything the horde society accomplished nowadays. The horde designed by Thrall are peoples who wants to be free in Azeroth, and to live in peace, garrosh wants to dominate Azeroth and is ready to enter a war with everyone who don't agree with him.
It's a massive régression : the horde, which was on the way to become a peaceful and unified community is dispersing cause of Garrosh, responsible of the internal conflicts between orcs & trolls / orcs & blood elves.

We've been told that patch 5.3 will not be a raid tier. If it's another patch in the vein of 5.1, in will in all likelyhood contain a lot of story related material that will move events towards the Siege of Orgrimmar in the final patch.

So we may not know exactly what Garrosh will do to turn much of the Horde against him, but there's a good chance that 5.3 is when we'll see it.

My theory is that it will include seizing control of a mogu machine and flesh-shaping tech for some kind of war plot, though I'm not sure what about that would finally tip the scales against him. I think it would be awesome, personally.

He turn against the Horde and become the final boss of MoP, as we know now.
Any information, what he do that the Horde turns aganist him?

He's going the same route as his father. He wants power and the Sha are very powerful and feared by everyone. From the 5.1 questline we know that when you get possessed by a Sha you'll become very powerful and the more power you want the less control you have. People with a weak will like the normal Korkron get swallowed by power and become a Sha. Stronger minds (like Nazgrim or Ishi) can control the power to a certain extent so that they don't transform into a Sha but lose their mind.

Garrosh thinks he can control the Sha and I think everyone can imagine what will happen when he gets infected by a Sha.

Would be fun if we could side with Garrosh, protecting him against waves of Rebel and Alliance filth.

The difference between a rebellion and a revolution is popular support. If Vol'jin's rebellion gains popular support among Horde citizens and enough of the orcish military defects to join him, it's a revolution at which point he'll be fondly remembered by history as well as misguided anarchists and rebellious teenagers (like Che Guevara, only without being an enormous douche).

Anyway, at some point, all but the most deluded Horde soldiers will apparently come to the conclusion that Garrosh is doing more harm than good and that the Horde has to get rid of him if it's going to survive. Therefore, it's generally safe to assume the AFGNAACP Horde Player Character is among the revolutionaries (it's actually implied as early as 5.1 that the Horde Player Character joins Vol'jin's underground, but puts on a facade of loyalty to Garrosh to do what they can to mitigate the damage he's doing).

He has both the Alliance and most of the Horde hating him now, because he pretty much screwed over the Sunreavers, betrayed Vol'jin, killed Cairne (accidentally, but nontheless), and Sylvanas - heck, she doesn't like ANYBODY. And because he's now experimenting with Sha energy, that'll make the incredibly forgiving Pandaren hate him as well.

Currently flailing around, mid-bubble, in order to heal the WoD content with his new main. Thank the light for Lay on Hands, right?

In general? His war and his behaviour is destroying the Horde.
He is sacrificing his 'allies' all the time because they are untermenschen compared to his Orcs.

Tauren: He killed their leader.
Trolls: He tried to kill their leader and took over their hometown.
Forsaken: He threatened their leader and used them as frontline-meat.
Blood Elves: He used them as frontline-meat too, to the point where they almost joined the Alliance.
Goblins: No info on that, but he will probably refuse to pay them
Orcs: He is trying to "upgrade" them with the Sha-power, after all the Burning Legion-crap they aren't happy with that.

He has both the Alliance and most of the Horde hating him now, because he pretty much screwed over the Sunreavers, betrayed Vol'jin, killed Cairne (accidentally, but nontheless), and Sylvanas - heck, she doesn't like ANYBODY. And because he's now experimenting with Sha energy, that'll make the incredibly forgiving Pandaren hate him as well.

The only accident involved in Cairne's death was that Garrosh was so ignorant of his own customs that he couldn't tell poison from ceremonial oils. The mak'gora had been upped to the death during the challenge.

What the tauren should have issues with Garrosh over are how Garrosh sat idly by when Magatha launched a bloody coup after Cairne's death (he literally did nothing but sent her a mean letter), forcing Baine to go to Jaina who, while at the time was very much a moderate, was also ostensibly Alliance and thus technically an enemy, then turns around and expects Baine to help him with every military operation the orcs engage in without fail, and the events that transpired in Baine's leader short story: he heavily taxes the tauren's water supply, overrules Baine's sovereignty in Mulgore and refuses to let Baine address the quillboar situation in his own way (and Baine's solution ultimately ends up solving the problem anyway), and nearly gets himself killed by underestimating the quillboar and has to get his ass pulled out of the fire by Baine and a squad of elite Sunwalkers.

1. Mana bombing Theramore. While most of the Horde cheered, the tauren and darkspear, or at least their leaders Baine and Vol'jin, did not like this. Baine has even told Garrosh that he will not tolerate another Theramore.

2. Enslaving molten giants, an act that could apparently potentially cause another cataclysm. Though this is more angering the Earthen Ring than the horde.

3. Using the Kor'kron as secret police to murder and harm his own people who speak against him.

4. Trying to assassinate Vol'jin. Though I'm not sure how this played out, if the kor'kron tried to assassinate him BECAUSE he spoke out against using the dark mogu magics, or if they were going to try and kill him anyway. Either way, they tried to assassinate Vol'jin and they put the Echo Isles under martial law.

5. Garrosh used the blood elves as fodder, his hasteful and reckless pushes into mogu ruins costing MANY blood elven lives. This nearly caused the blood elves to rejoin the Alliance, and only the Purge of Dalaran prevented this. Oddly enough they blame Garrosh as much as Jaina for that as well.

6. Using the Divine Bell to try and harness the power of the Sha. While the orcs with him didn't seem to mind this, even with their fellows being transformed into sha monsters, I'm sure many in the Horde don't like it.

And that's only what Garrosh has done SO FAR. I suspect 5.3 will see the revolution start to really unfold.

---------- Post added 2013-01-27 at 12:55 PM ----------

Originally Posted by Callei

The only accident involved in Cairne's death was that Garrosh was so ignorant of his own customs that he couldn't tell poison from ceremonial oils. The mak'gora had been upped to the death during the challenge.

What the tauren should have issues with Garrosh over are how Garrosh sat idly by when Magatha launched a bloody coup after Cairne's death (he literally did nothing but sent her a mean letter), forcing Baine to go to Jaina who, while at the time was very much a moderate, was also ostensibly Alliance and thus technically an enemy, then turns around and expects Baine to help him with every military operation the orcs engage in without fail, and the events that transpired in Baine's leader short story: he heavily taxes the tauren's water supply, overrules Baine's sovereignty in Mulgore and refuses to let Baine address the quillboar situation in his own way (and Baine's solution ultimately ends up solving the problem anyway), and nearly gets himself killed by underestimating the quillboar and has to get his ass pulled out of the fire by Baine and a squad of elite Sunwalkers.

Yeah, Cairne's death is NOT one of Garrosh's great crimes. Cairne accused Garrosh of crimes he was innocent of, challenged him, and Garrosh only upped it to a duel to the death to try and bluff Cairne into rescinding the challenge. Cairne was as much to blame for it as Garrosh himself was.

Yeah, Cairne's death is NOT one of Garrosh's great crimes. Cairne accused Garrosh of crimes he was innocent of, challenged him, and Garrosh only upped it to a duel to the death to try and bluff Cairne into rescinding the challenge. Cairne was as much to blame for it as Garrosh himself was.

In all honesty I would say Baine hasn't done too shabby a job so far. You know, given who he has to deal with.